Influence of iron nutrition in Pb-treated Ailanthus altissima (Mill.) Swingle seedlings was investigated by measurement of photosynthetic efficiency (Fv/Fm), photosynthetic pigment content, and biomass production. The data of Fe-sufficient and Fe-deficient hydroponically grown plants shows that the presence of Fe in growing media in Pb-treated plants increased Fv/Fm compared to Pb-treated plants without Fе. It was also reduced half time, requiring it to reach maximum fluorescence. Chlorophyll as well as carotenoid content did not decrease in Pb-treated A. altissima plants grown with Fe. There was also no significant reduction in root and shoot biomass in all Pb-treated plants when they were constantly supplied with Fe. These results suggest that Fe nutrition increase tolerance to Pb stress in A. altissima plants. This finding could be useful for improving recultivation methods on Pb-polluted sites.
Invasive plants are one of the major treat to local communities and ecosystems in urban habitats. Aster lanceolatus Willd. is one of the most spreading invasive plant species in Serbia and to examine its impact on soil, flora and aboveground biomass in urban habitats we investigated the pH, electrical conductivity and concentration of trace elements (Zn, Cu, Ni, Mn) in four invaded and four uninvaded plots in urban habitats. We also studied floristic composition and floristic richness regarding these invasive plant populations. These parameters were assessed along transects arranged in the cross shape, running from the centre of the invaded area towards the peripheral uninvaded area. Trace elements were analysed using atomic absorption spectrophotometer. Statistical differences were analysed using ANOVA and post-hoc LSD-tests. The results showed an important decrease of the number of species and herbaceous cover under A. lanceolatus populations. There were no statistically significant differences between invaded and uninvaded patches when soil pH and electrical conductivity were considered. The concentration of Zn, Mn and Ni in the soil was higher in invaded areas. The content of Zn in aboveground biomass collected from invaded compare to uninvaded areas was higher. This study raises the possibility that invasive species changes soil characteristics and create conditions for their spreading.